JP4251267B2 - AC motor fixed position stop control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixed position stop control device using an inverter having a multipoint stop positioning control function of a rotating body spindle driven by an AC motor.
[0002]
[Prior art]
FIG. 5 is a block diagram showing a conventional example of this type of fixed position stop control device, in which an AC motor 10, a transmission 11, a rotating body spindle 12, a position detector 13, a position detection circuit 14, a speed detection circuit 15, a position A control arithmetic circuit 16, a speed pattern selection circuit 17, an acceleration / deceleration arithmetic circuit 18, an inverter 20, and the like are included.
In such a configuration, a position detector 13 such as a pulse encoder is attached to the rotating body spindle 12 driven from the AC motor 10 via the transmission 11 or the like. The rotational position θ calculated by the position detection circuit 14 and the actual speed detection value N calculated by the speed detection circuit 15 from the position information are input to the speed pattern selection circuit 17.
[0003]
On the other hand, either a position control linear deceleration pattern calculation result calculated by the position control calculation circuit 16 or a slow speed setting value indicating a speed at which the parameter setting linear control pattern is shifted is set as a speed pattern selection circuit. The output obtained from the acceleration / deceleration calculation circuit 18 is input to the acceleration / deceleration calculation circuit 18, and the output from the acceleration / deceleration calculation circuit 18 is output as a speed command to a speed control block (not shown) in the inverter 20. The fixed position stop control is performed. FIG. 6 shows the above series of operations together with the time axis.
[0004]
[Problems to be solved by the invention]
When the positioning start command is input and the set value of the slow speed, which is the speed that moves from the deceleration ramp according to the normal deceleration time to the position control linear deceleration pattern, can be increased, the time to stop can be reduced. If the deceleration torque is increased too much to exceed the required capacity, it will not be able to stop at the target stop position and will overrun. On the other hand, if it is too small, the time to stop will be longer, so it should be set to an optimum value that does not overrun.However, since the setting is done artificially, the operation of the rotating body spindle should be performed while repeating the stop positioning operation. There is a problem that it requires a complicated and time-consuming work of changing the set value to see and artificially determining the optimum value according to the load condition of the system.
Accordingly, an object of the present invention is to optimize a slow speed for stop positioning control, and to eliminate a complicated and time-consuming work.
[0005]
[Means for Solving the Problems]
In order to solve such a problem, in the invention of claim 1, the AC motor fixed position stop control for stopping the AC motor, which is controlled by the inverter device and drives the rotating body spindle to which the position detector is attached, at the target position. In the device
From the maximum speed and deceleration time of the AC motor and the gear ratio between the AC motor and the rotating spindle, the maximum slow speed for shifting to a linear deceleration pattern that allows the AC motor to stop in the shortest time is calculated. An arithmetic means is provided.
[0006]
In the first aspect of the invention, when the slow speed is controlled by setting a parameter, a limiter for limiting the slow speed value set by the parameter so as not to exceed the calculated value from the calculating means is added. it is Ru can (the invention of claim 2).
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a first embodiment of the present invention.
As is apparent from FIG. 1, the slow speed calculation circuit 19 is added to the conventional example shown in FIG. The slow speed calculation circuit 19 calculates an optimum value of the slow speed as follows.
[0008]
FIG. 2 shows the state of the deceleration gradient α from the motor speed Na (r: number of revolutions / min: minutes) to the stop at the deceleration time Ta (s: seconds). Assuming that the motor speed is set as a parameter as the deceleration time Ta (s) in the shortest time from Na (r / min), the deceleration gradient α that can be decelerated is
α ≦ Na / Ta (1)
(However, when the motor characteristics and the load torque characteristics are both constant torque characteristics).
[0009]
On the other hand, as shown in FIG. 6, after deceleration at a deceleration slope according to a normal deceleration time, the speed becomes a slow speed, and after that speed is maintained, for example, the position control linear deceleration starts from one rotation before the main spindle stops. Thus, in the system that calculates the deceleration slope that can stop at the target stop position, the following relationship is established among the movement angle θ, the slow speed N1, and the deceleration time t.
θ (°) = (N1 / 60) × t × (360/2) (2)
[0010]
When the gear ratio between the motor and the spindle is spindle speed: motor speed = 1: n, the moving angle θ (°) of the motor when the spindle rotates once is θ (°) = 360 × n. From equation (2)
N1 = 120 n / t (3)
It becomes. When this relationship is expressed as a deceleration slope α,
α = N1 / t = N1 / (120n / N1) = N1 ² / 120n
Since this inclination α must satisfy the equation (1),
N1 ² / 120n ≦ Na / Ta
∴N1 ≦ √ (120 × n × Na / Ta) (4)
Thus, N1 that satisfies the equation relation is the maximum value that can be set as the slow speed.
[0011]
In general, Na / Ta is preset in the inverter as a deceleration slope during normal stop other than positioning, and the gear ratio n is uniquely determined from the machine configuration. The arithmetic circuit 19 can determine the slow speed N1 that can be positioned in the shortest time without overrun.
[0012]
FIG. 3 is a block diagram showing a second embodiment of the present invention.
Although it is almost the same as FIG. 1, it is characterized in that a limiter 21 for limiting the set value of the slow speed set by the parameter by the output value from the slow speed calculation circuit 19 is added. As a result, even if the parameter setting value for the slow speed is greater than or equal to the optimum value, it is limited to the optimum value, so it can be decelerated and stopped at the target stop position without overrun in multipoint stop positioning of the rotating body spindle. It becomes. In addition, when it is desired to slowly decelerate and stop at the target stop position, an arbitrary deceleration inclination can be set.
[0013]
FIG. 4 is a block diagram showing a third embodiment of the present invention.
This is different from the one shown in FIG. 1 in that the torque command τ in addition to the rotational position θ and the actual speed value (detected value) N calculated by the speed detecting circuit 15 are input to the slow speed calculating circuit 19. The point is to use.
That is, between the torque command τ, speed N, load inertia GD ² , and deceleration time t,
t = GD ² × N / (375 × τ)
That is,
375 × τ / GD ² = N / t
There is a relationship.
[0014]
Therefore, in the case of a vector control type inverter having a speed detection circuit, for example, the rate of change per unit time of the speed with respect to the torque command is obtained during normal acceleration / deceleration, for example, and the load inertia GD ² is estimated in advance from this. The speed calculation circuit 19 can automatically calculate the deceleration gradient (N / t) that can be decelerated by the maximum torque command.
[0015]
【The invention's effect】
As in the first aspect of the invention, it is not necessary to set the slow speed parameter by automatically determining the optimum slow speed value by giving the motor maximum speed Na, the deceleration time Ta, and the gear ratio n. There is an advantage that the operation with the shortest speed pattern is possible.
As in the second aspect of the invention, the optimum value for the slow speed is automatically determined by giving the maximum motor speed Na, the deceleration time Ta, and the gear ratio n, and the parameter setting value for the slow speed is limited to the optimum value. (Limit) makes it possible to decelerate and stop at the target stop position without overrun in the multi-point stop positioning of the rotating body spindle even when a setting greater than the optimum value is made. Even if it is necessary to set the slow speed parameter, if the set value is set larger than the optimum value, there will be no variation due to the adjustment personnel to adjust, and furthermore, if you want to slowly decelerate to the target stop position. It is also possible to set an arbitrary deceleration inclination.
As in the invention of claim 3, by automatically determining the slow speed optimum value according to the torque command from the inverter device, not only the slow speed parameter setting is not necessary, but also the operation in the shortest speed pattern The advantage is that it becomes possible.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a first embodiment of the present invention;
FIG. 2 is an explanatory diagram of a calculation principle of a slow speed.
FIG. 3 is a block diagram showing a second embodiment of the present invention.
FIG. 4 is a block diagram showing a third embodiment of the present invention.
FIG. 5 is a block diagram showing a conventional example.
6 is an operation explanatory diagram of FIG. 5. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... AC motor, 11 ... Transmission, 12 ... Rotating body main shaft, 13 ... Position detector, 14 ... Position detection circuit, 15 ... Speed detection circuit, 16 ... Position control arithmetic circuit, 17 ... Speed pattern selection circuit, 18 ... Acceleration / deceleration calculation circuit, 19 ... slow speed calculation circuit, 20 ... inverter device, 21 ... limiter.

Claims (2)

In the AC motor fixed position stop control device for stopping the AC motor, which is controlled by the inverter device and drives the rotating body spindle to which the position detector is attached, at the target position,
From the maximum speed and deceleration time of the AC motor and the gear ratio between the AC motor and the rotating spindle, the maximum slow speed for shifting to a linear deceleration pattern that allows the AC motor to stop in the shortest time is calculated. A constant position stop control device for an AC motor, characterized in that a calculation means is provided.   2. When the slow speed is controlled by setting a parameter, a limiter for limiting the slow speed value set by the parameter so as not to exceed a calculated value from the calculating means is added. A constant position stop control device for an AC motor as described in 1.

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